Abstract
Two rice cultivars of the high yielding semi-dwarf type, Vijayamahsuri and Sonamahsuri, and two cultivars of the tall scented type, HR 59 and Basmati, were investigated on their plant growth. Cultivar Vijayamahsuri showed the greatest productivity in dry matter of every plant organs, e.g., leaves, stems and roots. LAI of cv. Vijayamahsuri was also greatest. In cv. Basmati, a shallow planting of 2.3 cm in depth was apparently effective in increasing the number of tillers, dry matter production, root length and LAI. High yielding cultivars Vijayamahsuri and Sonamahsuri showed a similar tendency of the light distribution in the plant canopy, indicating the same value of the light extinction coefficient (0.29). In contrast, plant populations of cvs. HR 59 and Basmati showed rather lower values of extinction coefficient, that is, the lower parts of the populations could receive a relatively high intennsity of the light. Chlorophyll contents of the upper four leaves varied with cultivars as well as with the leaf position on the culm. It is of interest that in chlorophyll contents of the leaves, cvs. Vijayamahsuri and Sonamahsuri exceeded cvs. HR 59 and Basmati and either the second or the third leaf from the top is highest in most cases. We consider that a high efficiency in dry matter production in cvs. Vijayamahsuri and Sonamahsuri are mainly due to higher content of chlorophyll of the leaves.
